POSITIVE ELECTRODE ACTIVE MATERIAL

摘要

A highly effective positive electrode is obtained by using a material such as Na which is an inexpensive abundant resource. A positive electrode active material of sodium transition metal phosphate of olivine structure in which the sodium transition metal phosphate of olivine structure includes, a phosphorus atom that is located at the center of a tetrahedron having an oxygen atom in each vertex, a transition metal atom that is located at the center of a first octahedron having an oxygen atom in each vertex; and a sodium atom that is located at the center of a second octahedron having an oxygen atom in each vertex, and adjacent sodium atoms are arranged one-dimensionally in a <010> direction.